Len McCluskey has hit out at what he calls the “intransigent hostility” of Jewish community leaders and accused “Blairite” Labour MPs of exploiting the anti-Semitism row to provoke a split in the party.

Writing for HuffPost UK on Thursday afternoon, the general secretary of the Unite union and close ally of Jeremy Corbyn, said Labour risked descending “into a vortex of McCarthyism”.

Corbyn and the party have been engulfed in controversy after failing to endorse the International Holocaust Remembrance Alliance’s (IHRA) definition of anti-Semitism in its entirety.

The Labour leader has also come under fire for attending a controversial event at a Palestinian Martyrs Cemetery in Tunis in 2014.

McCluskey said today the problem of anti-Semitism in the party was “not manufactured but has certainly been wildly exaggerated by now”.

“I am at a loss to understand the motives of the leadership of the Jewish community – the Board of Deputies, the Jewish Leadership Council and the Jewish Labour Movement,” he said.

“They raised entirely proper concerns, but have simply refused to take ‘yes’ for an answer.”

McCluskey said the “more Corbyn has personally sought to build bridges” with the Jewish community “the worse the rhetoric has become”.

“What is the response from the leading Jewish community organisations to this record of reaching out, of understanding, and of action? Intransigent hostility and an utter refusal to engage in dialogue about building on what has been done and resolving outstanding difficulties,” McCluskey said.

He added: “I therefore appeal to the leadership of the Jewish community to abandon their truculent hostility, engage in dialogue and dial down the rhetoric, before the political estrangement between them and the Labour Party becomes entrenched.”

The union boss said the leadership of the Jewish community should “grasp the hand stretched out towards them”.

And he accused the three newspapers; the Jewish Chronicle, Jewish News and Jewish Telegraph; that claimed Corbyn was an “an existential threat to Jewish life” of a “thoroughly irresponsible act of fear-mongering”.

Len McCluskey Blog...

McCluskey also said Labour should now adopt all eleven IHRA examples as not having done so was “insensitive”.

But he warned there remained “free-speech problems” with the example concerning ‘Israel as a racist endeavour’.

“While rooting out the anti-Semites, we cannot descend into a vortex of McCarthyism, however much Labour’s opponents might enjoy the spectacle,” he said.

The Unite leader used his blog to accuse Chuka Umunna and other Labour MPs of using the row over anti-Semitism as a method to “provide rocket fuel for a split in the Party”.

“Let those few Labour MPs looking to break away from the Party do so on an honest basis, embracing capitalism, the free market and the alliance with Trump’s America, and not pretend that Labour is something it is not, an institutionally racist Party,” he said.

In response, Umunna said he would not be “bulled into silence” by McCluskey.

I stand by what I've said on racism in the Labour Party and won't be bullied into silence, not least because my family have experienced racism too. Jeremy Corbyn himself has said it is a problem Labour has not properly dealt with. If Len McCluskey doesn't like that, so be it. /1

Len McCluskey asks for "serious evidence" of institutional discrimination in the Labour Party against Jewish people - I set out in detail why it is wholly justified to reach this conclusion many weeks ago here https://t.co/lx8bN00ao3 /2

Instead of attacking the victims of racism, our values dictate that we stand up for them -that is what I have done. Its shameful the General Secretary of the union of which I am a member should make a personal and political attack against me instead of facing up to this issue. /3

After the blog was published, the Board of Deputies, which is the main representative body of British Jews, said: “We note that Len McCluskey has advocated the adoption of the full IHRA definition of anti-Semitism and its illustrative examples.

“However, his attack on the Jewish community is both unfair and unwarranted.”

The spokesman added: “We have had a deluge of words from the Labour leadership.

“It is about time that the party resolved this crisis by taking the firm and decisive action which the communal leadership set out for them in detail months ago.

She said: “I find that offensive, I think that’s trivialising the issue of anti-Semitism to pretend that somehow we’re using that for cheap party political purposes. I’m not, and I think most of those colleagues who are with me, Jews and non-Jewish MPs feel exactly the same as I do.”

In an interview with Sky News, the former Labour minister told how when she learned of the investigation she “kept thinking what did it feel like to be a Jew in Germany in the Thirties”.

Labour MP Ian Austin, who is also being investigated over his behaviour during a row about the party’s anti-Semitism code. said: “Len McCluskey’s article on Labour’s anti-Semitism crisis is disgraceful.

“It is outrageous to blame the Jewish community for the immense distress they feel and the offence that’s been caused.

“Labour MPs are right to demand it is sorted out. We won’t be bullied into silence on this.”